RESUMEN
A hybrid glucose microfluidic fuel cell composed of an enzymatic cathode (Laccase/ABTS/C) and an inorganic anode (AuAg/C) was developed and tested. The enzymatic cathode was prepared by adsorption of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and Laccase on Vulcan XC-72, which act as a redox mediator, enzymatic catalyst and support, respectively. The Laccase/ABTS/C composite was characterised by Fourier Transform Infrared (FTIR) Spectroscopy, streaming current measurements (Zeta potential) and cyclic voltammetry. The AuAg/C anode catalyst was characterised by Transmission electron microscopy (TEM) and cyclic voltammetry. The hybrid microfluidic fuel cell exhibited excellent performance with a maximum power density value (i.e., 0.45 mW cm(-2)) that is the highest reported to date. The cell also exhibited acceptable stability over the course of several days. In addition, a Mexican endemic Laccase was used as the biocathode electrode and evaluated in the hybrid microfluidic fuel cell generating 0.5 mW cm(-2) of maximum power density.
Asunto(s)
Fuentes de Energía Bioeléctrica , Lacasa , Técnicas Analíticas Microfluídicas/instrumentación , Benzotiazoles , Coriolaceae/enzimología , Técnicas Electroquímicas , Enzimas Inmovilizadas , Diseño de Equipo , Oro , Técnicas Analíticas Microfluídicas/métodos , Plata , Espectroscopía Infrarroja por Transformada de Fourier , Ácidos SulfónicosRESUMEN
The State of Hidalgo (Mexico) has a large area of forests known as the Huasteca Hidalguense, with a large variety of microorganisms inhabiting it. They represent an important resource from the ecological and technological point of view because they can be used in a broad variety of industrial processes. Due to the climatic conditions of this region, fungi inhabiting it must be thermophile or, at least, thermotolerant, as temperatures can be higher than 45°C in the summer, declining to 20°C in the winter. Use of ligninolytic fungi relies on their capacity to produce enzymes of industrial interest, a topic that has been under continuous research by academic and industrial investigators. Among the most important enzymes are proteases that are widely used due to their biotechnological applications with a high economic impact. Other enzymes, laccases, peroxidases, and lipases are of interest for the industries of the state of Hidalgo, especially in the textile industry, specifically in effluent processing. Fungi (n=156) were collected in the Huasteca Hidalguense, of which 100 were isolated in potato-dextrose-agar covered plates and maintained in tilted tubes. Afterwards, enzymatic activity (laccase, protease and lipase) was determined in the plates. The purpose was to select those fungi with the highest potential for biotechnological applications. Fungi generally grew at either 30°C or 37°C, and for some isolates enzymatic activities were detected at this higher temperature. Results are presented as the relation between enzymatic activity and growth rate: 60 fungi presented laccase activity, 49 had lipase activity, and none had protease activity. In most cases, enzymatic activity was higher than the growth rate, indicating that the isolated fungi have a great biotechnological potential. Statistical analysis revealed that isolates 31 (Trametes) and 8.1 (unidentified) have a larger potential to be studied as laccase-producing fungi. On the other hand, isolates 144.2 (Fomes), 154 (Trametes), and 147.2 (Pycnoporus) are of interest as lipase activity producers, an activity scarcely studied in this type of microorganisms.
Asunto(s)
Hongos/enzimología , Hongos/aislamiento & purificación , Lacasa/metabolismo , Lipasa/metabolismo , Péptido Hidrolasas/metabolismo , Coriolaceae/enzimología , Coriolaceae/aislamiento & purificación , Hongos/crecimiento & desarrollo , Microbiología Industrial/métodos , Lignina/metabolismo , México , Pycnoporus/enzimología , Pycnoporus/aislamiento & purificación , Temperatura , Trametes/enzimología , Trametes/aislamiento & purificaciónRESUMEN
In a previous paper, the authors showed that a slight aeration of a methanogenic reactor treating wastewater from the manufacture of polymeric resins could improve its performance, by increasing or allowing the removal of some of its contaminants, including vinyl acetate (VA). This paper reports the isolation under aerobic conditions of a VA-biodegrading axenic culture (strain C1) retrieved from the sludge of a slightly aerated methanogenic reactor at 1 mg L(-1) d(-1) of dissolved oxygen (DO). The axenic culture obtained was phenotypically (morphology, biochemical properties, VA consumption kinetics) and phylogenetically characterized. It formed white colonies with a branched and flat morphology on solid medium. The cell morphology of the isolate was bacillus with round endings and flagellate. The cells could form chains and were stained Gram-negative. The isolate required simple nutritional elements and had a growth rate of 0.024 h(-1). The phylogenetical analysis showed that the aerobic bacterium was identified as Brevibacillus agri, with 99.3% similarity. The VA consumption kinetics in the methanogenic sludge were: volumetric consumption rate (rVA) of 1.74 +/- 0.2 mg L(-1) h(-1), maximum specific consumption rate (qVAmax) of 3.98 mg g(-1) volatile suspended solids (VSS) h(-1) and affinity constant (Ks) of 457.1 mg L(-1). The same parameters in the axenic culture were 1.69 +/- 0.04 mg L(-1) (h-1), 4.09 mg g(-1) dry weight h(-1) and 421.9 mg L(-1), respectively. These results show evidence that the aerobic isolated bacterium, identified as Brevibacillus agri, carried out the VA hydrolysis in the slightly aerated methanogenic sludge, which is the limiting step in the degradation of this compound.